1. Field of the Invention
The present invention relates to a brush cleaning device for electrophotographic reproducing apparatus and more particularly to a brush cleaning device in which magnetic toner powder remaining on the image receptor after the image transfer process is removed from the image receptor by a fur brush.
2. Description of the Prior Art
In a general brush cleaning device used with electrophotographic reproducing apparatus, the rotation of a fur brush sends magnetic toner powder flying in the space within the apparatus. To recover the toner powder into a filter, a blower is incorporated in the apparatus making it large in size and noisy during operation.
To solve this problem, a device such as shown in FIG. 1 has been proposed. In this device, a non-magnetic cylindrical sleeve 3 is placed near the fur brush 1 which brushes off magnetic toner from the image receptor 2; a magnetic member 5 is placed inside the cylindrical sleeve 3 to attract the magnetic toner released from the fur brush by a flicker member 4 onto the external surface of the sleeve 3; and the magnetic toner on the cylindrical sleeve 3 is scraped off by a scraper 6 and recovered. This type of brush cleaning device has little toner powder flying in the device and thus does not require a blower, which in turn enables reduction in the size of the device and results in little fatigue of the magnetic toner. Despite these features, the proposed device has the following drawbacks in recovering the magnetic toner for reuse. The first problem is that broken hair of the fur brush 1 mixes with the recovered toner, which will cause problems. The second problem is that a device such as a magnetic toner discharging screw must be provided where the magnetic toner is to be collected, and this increases the number of parts and makes difficult the size reduction of the device.
As a means for carrying powder, a device such as a screw conveyor is known which is formed of a combination of a cylindrical tube and a coil which carries powder by rotation of the coil. In such devices the powder near the bottom of the tube is acted upon by a strong force due to gravity and may be hardened or impaired. Further, the powder carrier path is limited almost to a linear path and no large abrupt change in height is allowed for the path. The screw conveyor could not be relied upon to move a constant amount of powder.